This invention relates to the field of paging simulcast transmission systems and specifically to a simulcast transmission system in which each individual simulcast transmitter in the system can be individually activated or "knocked down" in response to a signal from a paging terminal or central controller.
In the past simulcast transmission systems have incorporated transmitting stations which remained activated while the simulcast system was in use. Individual remote station control systems have not been developed with efficient signalling schemes.
Wide area coverage systems employing multiple transmitters on the same RF channel are gaining wider acceptance due in part to the growth of personal paging activity. Simulcast transmission systems require that each transmitter in the system produce a signal of substantially identical frequency and modulation. This requires that the transmitting stations in a simulcast system be periodically adjusted so that critical system parameters are satisfied. One method of calibrating a simulcast transmission system is to selectively deactivate certain transmitters in the system while active transmitters are adjusted. In a typical prior art simulcast transmission system, service personnel would be stationed at each individual transmitter location, and would communicate through a separate telephone line or RF channel while manually activating and deactivating remote simulcast transmitters to effect the calibration procedure. Prior art simulcast systems have not included any means for individually, efficiently and remotely controlling simulcast transmitters through a conventional simulcast system link.
In addition, individual simulcast transmitter control is useful in a simulcast system which is designed to generate multiple signalling schemes. A simulcast transmitter which can generate both binary and analog signalling formats, can be configured for individual station control and provide a truly universal paging system with controllable area coverage. For instance, simulcast system would typically be configured to provide wide area coverage in a certain area. However, paging subscriber may desire service in only a portion of the total available area, for instance at a large construction site in a certain sector of a city. A simulcast transmission system with individual station control can provide service to the limited area subscriber without requiring the subscriber to pay a fee based on broad area coverage. In other words, another benefit of individual station control is the ability to sector paging coverage based on different tariff structures.